1. Field of the Invention
The present invention relates to a light emitting device and a method of manufacturing the same, and more particularly, to a light emitting device, wherein trenches of a mesh structure are formed by etching a P-type semiconductor layer and an active layer to expose an N-type semiconductor layer and a conductive layer is formed by being filled in the trenches, and a method of manufacturing the same.
2. Description of the Related Art
In general, since nitrides, such as GaN, AlN and InN, have an excellent thermal stability and a direct-transition-type energy band structure, they have recently come into the spotlight as materials for photoelectric devices in blue and ultraviolet regions. Particularly, since GaN has a very large energy bandgap of 3.4 eV at normal temperature, it may be used as a high-temperature and high-output device. Since the GaN is combined with a material such as InN or AlN and an energy bandgap of the GaN can be controlled from 1.9 eV (InN) to 3.4 eV (GaN) or 6.2 eV (AlN), the GaN can emit light in a broad wavelength range of visible light to UV light. For this reason, the GaN is a material having high applicability to optical devices.
A light emitting device using GaN generally includes an N-type GaN layer, an active layer and a P-type GaN layer, which are laminated and formed on a substrate, and N-type and P-type electrodes respectively connected to the N-type and P-type GaN layers. When a predetermined current is applied to the N-type and P-type electrodes of the light emitting device, electrons provided from the N-type GaN layer and holes provided from the P-type GaN layer are recombined in the active layer, thereby emitting short-wavelength light corresponding to green or blue.
Since the P-type GaN layer has a low conductivity, a conductive layer is formed on the P-type GaN layer so that current is effectively diffused. The conductive layer is formed to have a double-layered structure of Ni and Au of a few tens to a few hundreds of angstroms (Å). However, since when using the double-layered structure of Ni and Au, the transparency thereof is lowered and photons are absorbed therein, the quantum efficiency is lowered. A high-efficiency light emitting device should simultaneously have a characteristic of current uniformly diffused in a large area and a high external quantum effect. To this end, the transparency is improved by forming a transparent electrode between the P-type GaN layer and the P-type electrode, and the current diffusion characteristic is improved by forming an extension electrode extending from the P-type electrode. The extension electrode is connected to the P-type electrode and formed to extend along the outline of the light emitting device in the shape of a wing. However, even when the extension electrode is formed as described above, current is not uniformly diffused, and therefore, light is not uniformly emitted. That is, light emitted between the P-type electrode and the extension electrode adjacent to the P-type electrode is dark, and light emitted between the N-type electrode and the extension electrode adjacent to the N-type electrode is bright.